It said that people had expressed concerns about the offers "for the private sales of firearms" on the site.

"It is one of many areas where we face a difficult challenge balancing individuals' desire to express themselves on our services, and recognizing that this speech may have consequences elsewhere."

The firm said that it had worked with various stakeholders, including New York Attorney General Eric Schneiderman, to develop the new rules.

Under the guidelines, private sellers of firearms in the US will not be permitted to specify "no background check required", nor can they offer to transact across state lines "without a licensed firearms dealer".

The new regulations, which will be enforced in the coming weeks, will also apply to its photo sharing site Instagram.